ON AIR FROM OFF THE MID-AILANTIC. 181 



viewed by transmitted lights they are seen to consist of a 

 collection of spheres of graduated sizes^ the largest nearly, 

 but not quite, enclosing all the others. In the ordinary 

 GlobigerincB, the chambers are formed in succession, as they 

 are needed to protect additional growths of the animal, the 

 sarcode collecting from the outer surface of the already 

 formed shell into the globular shape peculiar to the species, 

 and placing itself in advance of the other chambers ; but 

 in the examples now under consideration this sarcode re- 

 tains its position as a coating over the whole surface of the 

 existing shell, and there acquires its shell-covering; the 

 only difference, therefore, between these globes with an 

 irregular surface and those having the Globigerina com- 

 pletely enclosed within the outer sphere, is dependent on 

 the greater or less amount of sarcode requiring to be covered 

 by this last chamber. In both cases alike the next enlarge- 

 ment needed will involve the withdrawal of the animal 

 from the shell and the formation of an entirely new one, 

 which will then appear in the characteristic form of Orbu- 

 lina, as a simple hollow sphere. 



XI. On Air from off the Mid- Atlantic, and from some 

 London Law Courts. By E. Angus Smith, Ph.D., 

 F.R.S., &c., President. 



Read February 20th, 1866. 



As my friend Mr. Alfred Fryer was going to the West 

 Indies and America, I made up a box of tubes to hold 

 specimens of air, adding also apparatus for its collection. 

 He has brought me back some of the tubes fiUed; the 

 rapidity of his movements prevented him from obtaining 

 many. As Mr. Fryer is known to be a skilful experimenter, 

 we may be sure that the specimens are well preserved. 



